A wafer type butterfly valve which is sandwiched and mounted between flanges of a pipe to open and close a pipeline is conventionally known. Such butterfly valves are generally used for controlling fluid which is supplied to a plant equipment in various industrial fields.
As such a butterfly valve, there is a proposed structure in which in order to prevent condensation from being caused on a valve shaft cylindrical portion or an actuator which are opposed to atmosphere due to a temperature difference between atmospheric air and fluid which flows through a pipe, the valve shaft cylindrical portion is made of heat insulator (e.g., synthetic resin) which is different from material of the valve body so that a temperature of the fluid flowing through the valve body is not transmitted to the valve shaft cylindrical portion or the actuator, thereby preventing condensation from being cause. When the valve body and the valve shaft cylindrical portion are made of different materials, a joining structure therebetween is important. A disk-like valve element is disposed in the valve body. In order to drive and rotate the valve element, a valve rod outwardly extends in the valve shaft cylindrical portion. The valve rod is connected to the actuator which is mounted to an outer end of the valve shaft cylindrical portion. Since a torsional stress is applied to the coupled portion between the valve body and the valve shaft cylinder, a strong connecting structure is required. Japanese Patent No. 3026251 discloses one example of the butterfly valve which prevents the condensation. In the butterfly valve disclosed in this publication, connection grooves and connection legs which allow connecting portions of the valve body and the valve shaft to fit to each other are disposed around the valve shaft cylindrical portion at distances from one another, the connection grooves and the connection legs are engaged with each other to ensure the strength against the torsional stress, they are connected to each other using screws to prevent the connection legs from coming out from the connection grooves but they can be separated from each other. In such a structure, however, when the connection leg is fitted into the connection groove, if there is a gap therebetween, a rattle is generated, which may damage the connection groove and the connection leg. Therefore, precise machinability is required, and a plurality of connection grooves and connection legs must be provided around the valve shaft cylindrical portion at equal distances from one another, and the costs adversely increase.
The valve body comprises a valve body made of rigid material such as metal which passes through a cylindrical flow passage, a disk-like valve element which is rotatably pivotally supported by a valve rod in the valve body, and a sheet ring made of elastic material. The sheet ring is interposed between an inner peripheral surface of the valve body and the valve element. An outer peripheral surface of the valve element is brought into contact with and disengagement from an inner peripheral surface of the sheet ring to open and close the flow passage. The sheet ring of the butterfly valve is made of elastic material. When the valve is closed, the sheet ring is brought into contact with and engagement in the inner peripheral surface of the sheet ring under pressure, thereby securing sealing ability, and when the valve is closed, a great repulsion is generated by pressure-contact between the sheet ring and the valve element, and the rotation torque of the valve element is increased. There is a tendency that the sheet ring is fallen off from the valve body by a suction force caused by fluid or by a dragging force caused by pressure-contact with the valve element. In order to prevent the sheet ring from falling off from the valve body, there is a proposed structure in which opposite side surfaces of the sheet ring are fitted to a peripheral side surface of the valve body, the outer peripheral surface of the sheet ring is mounted to the inner peripheral surface of the valve body with a necessary compression margin to exhibit elastically fastening force. Japanese Patent No. 3188680 proposed a structure in which a projecting stripe is provided on a central portion of the outer peripheral surface of the sheet ring, the projecting stripe is fitted into a recess formed in a central portion of an inner peripheral surface of the valve body, thereby preventing the sheet ring from moving. In any of the structures, however, the sheet ring is strongly mounted so that the inner peripheral surface of the valve body does not move. When the valve is closed, elastic repulsion force of the sheet ring when the valve element comes into contact with the inner peripheral surface of the sheet ring becomes great, the rotation torque of the valve element is increased, and it is difficult to open and close the valve.
Further, the valve rod which rotatably pivotally supports the valve element is pivotally supported by a valve rod shaft supporting portion and is extended outward in a radial direction of the valve body. An actuator is connected to an outer end of one of the valve rods such that the actuator can drive and rotate. The other valve rod is sealed by a lid body mounted to an outer end of the valve rod shaft supporting portion and is shaft-sealed. One example of the shaft seal apparatus is disclosed in Japanese Patent Application Laid-open No. 2002-181203. According to the shaft seal apparatus disclosed in this publication, a bush is interposed between the valve rod and a valve rod shaft supporting portion of the valve body, and it is necessary to dispose an O-ring between the bush and the valve rod shaft supporting portion and the valve rod to seal therebetween, the sealing structure becomes complicated, it is necessary to fasten a lid body which seals an outer end of the valve rod shaft supporting portion using screws, which is troublesome and inconvenient.
Further, an actuator is connected to one of the valve rods which rotatably and pivotally supports the valve element to drive and rotate the valve rod. A manual gear type actuator is generally and widely employed as this actuator. According to this manual gear type actuator, a worm gear mechanism in which a worm wheel and a worm are meshed with each other is incorporated in a gear box, a valve rod is connected to the worm wheel, a manual handle is connected to the worm, and the valve element is rotated and driven manually. This manual gear type actuator is disclosed in Japanese Patent No. 3090420. A gear box of the conventional manual gear type actuator disclosed in this publication is usually a metal molded product such as an aluminum die casting. The gear box is filled with lubricant which lubricates a worm gear incorporated in the gear box. A stopper comprises a screw for aligning a valve element to a fully opened position and a fully closed position to stop worm wheel in a angle of 90 degree rotation range, so that the stopper position is adjusted. However, in order to effectively utilize a building in recent years, the gear box is disposed in a room where a normal work is carried out without providing a machine room underground in many cases, and there is a problem that a floor or a wall surface in the room is contaminated by grease leaking from the gear box. Further, since the adjusting screw is used, a structure of the gear box is complicated, and there is also a problem that condensation is caused on an outer surface.
Problems that this Invention is to Solve
First object of this invention is to precisely joint a valve body and a valve shaft cylindrical portion which are made of different materials such as metal and synthetic resin using relatively easily machining operation, thereby exhibiting sufficient strength against a torsional stress, and to prevent the valve body and the valve shaft cylindrical portion from falling off from each other using a simple structure.
Second object of the invention is to mount the sheet ring to the inner peripheral surface of the valve body with sufficiently great elastic fastening force, and to stably mount the sheet ring, and to reduce a rotation torque of the valve element.
Third object of the invention is to reliably seal a shaft seal of a valve rod which rotatably and pivotally support the valve element with a simple structure.
Fourth object of this invention is to solve problems concerning leakage of grease, generation of condensation and complication of a structure which are found in the manual gear type actuator.
Means for Solving the Problems
The present invention provides a butterfly valve in which a cylindrical flow passage is formed in the valve body such as to penetrate the valve body, a sheet ring made of elastic sealing material is mounted in the valve body, a disk-like valve element which comes into contact with and separates from the sheet ring is rotatably and pivotally supported by the sheet ring, a valve rod shaft supporting portion is formed in a radial direction of the valve body, the valve rod shaft supporting portion pivotally supports valve rods which pivotally support the valve element, an actuator is connected to an outer end of one of the valve rods, thereby driving and rotating the valve element, wherein a portion of the one valve rod which extends outward is pivotally supported, the valve shaft cylindrical portion which is connected to the valve rod shaft supporting portion is made of material different from that of the valve body, the ends of the valve shaft cylindrical portion and the valve rod shaft supporting portion are formed into rectangular cylindrical recess and projection which are fitted to each other, a fitting projection and a fitting groove which fit to fitting surfaces of the valve shaft cylindrical portion and the valve rod shaft supporting portion are formed, a connection pin is driven into the fitting portions of the valve shaft cylindrical portion and the valve rod shaft supporting portion and they are connected to each other in a falling-out preventing state. Preferably, the valve body is molded using aluminum die cast, the valve shaft cylindrical portion is molded using synthetic resin having insulative properties, iron-based casting or metal material which is different from that of the valve body. A thickness of an inner surface angle portion of the recess with which an angle portion of the projection comes into contact upon reception of torsional stress from the actuator is made thick, the fitting projection and the fitting groove are located near this thick angle portion.
A compression margin of the sheet ring with respect to an inner peripheral surface of the valve body is set such that the compression margin is small at a central portion of the sheet ring and the compression margin is great at opposite sides of the sheet ring so that the sheet ring is held by the inner peripheral surface of the valve body by an elastic fastening force at the opposite sides, the central portion of the sheet ring with which the valve element comes into contact under pressure is allowed to move slightly together with the valve element, and a movable torque of the valve element is reduced. Preferably, a slanting surface is formed between the inner peripheral surface and the outer peripheral surface of the sheet ring, an angle and a width formed by the slanting surface and the outer peripheral side surface are the greatest at a position intersecting with the valve shaft at right angles and are the smallest at a position of the valve shaft. A central portion of an inner peripheral surface of the valve body is allowed to project inward to form an engaging projection, a recess groove into which the engaging projection is formed in the outer peripheral surface of the sheet ring, and the sheet ring is held by engaging the engaging projection and recess groove with each other. A slanting surface is formed between the inner peripheral surface and the outer peripheral surface of the sheet ring, an angle and a width formed by the slanting surface and the outer peripheral side surface are the greatest at a position intersecting with the valve shaft at right angles and are the smallest at a position of the valve shaft.
Further, a cylindrical bush whose one end is closed is inserted into the other valve rod, an inner end of the bush is brought into contact with the sheet ring under pressure to seal the valve rod, and outer end of the bush is supported in a falling-out preventing state by means of a pin which is driven into the valve rod shaft supporting portion. Preferably, an O-ring is interposed between the bush and the valve rod shaft supporting portion to seal a gap therebetween, and a knob is formed on an outer end of the bush for taking out the bush.
Further, the actuator comprises a coupled body of upper and lower gear boxes in which a manually driven worm gear mechanism is integrally incorporated in the gear box, both the upper and lower gear boxes are molded products made of synthetic resin, a stopper portion which limits a rotation range of the worm gear mechanism is integrally formed in the gear box, one connection peripheries of the upper and lower gear boxes are formed with upper standing walls to which the other peripheries are fitted, the upper standing wall is provided at its outer side with a sealing projection.
Further, the invention provides a butterfly valve in which a cylindrical flow passage is formed in the valve body such as to penetrate the valve body, a sheet ring made of elastic sealing material is mounted in the valve body, a disk-like valve element which comes into contact with and separates from the sheet ring is rotatably and pivotally supported by the sheet ring, a valve rod shaft supporting portion is formed in a radial direction of the valve body, the valve rod shaft supporting portion pivotally supports valve rods which pivotally support the valve element, an actuator is connected to an outer end of one of the valve rods, thereby driving and rotating the valve element, wherein a portion of the one valve rod which extends outward is pivotally supported, the valve shaft cylindrical portion which is connected to the valve rod shaft supporting portion is made of material different from that of the valve body, ends of the valve shaft cylindrical portion and the valve rod shaft supporting portion are formed into rectangular cylindrical recess and projection which are fitted to each other, a fitting projection and a fitting groove which fit to fitting surfaces of the valve shaft cylindrical portion and the valve rod shaft supporting portion are formed, a thickness of an inner surface angle portion of the recess with which an angle portion of the projection comes into contact upon reception of torsional stress from the actuator is made thick, the fitting projection and the fitting groove are located near this thick angle portion, a connection pin is driven into the fitting portions of the valve shaft cylindrical portion and the valve rod shaft supporting portion and they are connected to each other in a falling-out preventing state, the valve body is molded using aluminum die cast, and the valve shaft cylindrical portion is molded using synthetic resin having insulative properties, a slanting surface is formed between the inner peripheral surface and the outer peripheral surface of the sheet ring, an angle and a width formed by the slanting surface and the outer peripheral side surface are the greatest at a position intersecting with the valve shaft at right angles and are the smallest at a position of the valve shaft, a central portion of an inner peripheral surface of the valve body is allowed to project inward to form an engaging projection, a recess groove into which the engaging projection is formed in the outer peripheral surface of the sheet ring, the sheet ring is brought into contact with the inner peripheral surface of the valve body under pressure in the opposite sides of the recess groove, the cylindrical bush whose one end is closed is mounted to the other valve rod which pivotally supports the valve element, and the other valve rod is sealed.
Effect of the Invention
According to the present invention, the valve body and the valve shaft cylindrical portion are made of different materials, they are connected with each other with sufficient strength against the torsional stress, and it is possible to reliably prevent the valve from being damaged by the torsional stress and to prevent rattle from being generated. The falling-out in the axial direction can also be prevented reliably, and it is possible to provide an extremely excellent connection structure between the valve body and the valve shaft cylindrical portion made of different materials.
It is possible to mount the sheet ring to the inner peripheral surface of the valve body with sufficiently great elastic fastening force, and to stably mount the sheet ring. A rotation torque of the valve element can be reduced.
Further, the shaft seal of the valve rod can be achieved with a simple structure in which the bush is inserted into the valve rod and is fixed using a pin. It becomes easy to automate the shaft seal of the valve rod.
Further, since the upper and lower gear boxes are molded using synthetic resin, the size precision is enhanced, the stopper can be integrally formed. Since opening adjusting means by means of a screw is not required, the entire structure can be simplified, and the costs can be reduced. Since synthetic resin having insulative properties is used, it is possible to effectively prevent condensation. It is easy to obtain a greaseless structure using resin having higher lubrication ability. This greaseless structure can solve the problem of contamination of a room floor and a wall surface caused by leakage of grease, and this structure is extremely beneficial.